The capacitance is measured between the inner and the outer electrode ring. The inner electrode ring is insulated with PTFE, and the outer ring is made of acid resistant steel (AISI 316). If a
liquid enters the gap between the two electrode rings, the capacitance will be altered. This change in capacitance is used to detect liquid / no liquid.

The GL-7B Level Switch can be used both in conducting and non-conducting liquids. The switches do not require any re-adjustment due to different types of cargoes (liquids). Both single and dual
types are available. Functional test of switch and electronics is carried out by means of a small permanent magnet.